Oil blast circuit breaker



NOV. 1933- 5. J. SPURGEON OIL BLAST CIRCUIT BREAKER Filed April 15. 1932uummm W b a 00% His Attor-h g.

Patented Nov 7, 1333 011. BLAST cmourr BREAKER Samuel J. Spurgeon,Birmingham, Ala., assignor to General Electric Company, a corporation ofNew York Application April 13, 1932. Serial No. 604,955

' 6 Claims. (01. 200-150) Myinvention relates to electric circuitinterrupters, and more particularly to circuit interrupters of theoil-blast type wherein a blast of insulating liquid is directed acrossan are causing interruption of the circuit.

- The principal object of my invention is the provision of an improvedcircuit interrupter of the aforesaid type which shall be positive andefficient in operation, and simple and compact in construction for agiven interrupting capacity rating.

My inventionwill be more fully set forth in the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with-particularity in theclaims annexed to and forming a part of this specification.

Referring to the drawing, Fig. 1 an elevational View, partly in section,.-of circuit interrupting apparatus embodying my invention and Fig. 2 isa similar view, partly in section, illustrating another form of myinvention.

The circuit interrupting apparatus shown in Fig. 1 comprises relativelymovable contact structure including a pair of fixed contacts 1 and 2 anda coacting movable bridging member 8 forming two breaks in seriesarranged so that separation of the contacts occurs within an;insulatingThe fixed contacts 1 and 2 are supported at the lower ends of theinsulating bushings 6 and 7, respectively, through which the lead-incon- .ductors 8 and 9 extend connecting with the fixed contacts. Inorder to provide for a limited amount of overtravel of the bridgingmember 3 at the end of the circuit closing operation, the contacts 1 and2 are each resiliently mounted with respect to conductingstuds 10 and11. The resilient con nections comprise springs 12 and 13 mounted onguide stems 14 and 15, respectively, which are slidably mounted forlimited movement within the studs 10 and 11. The bridging member 3,which may be actuated as by the lift rod 16, is of suitable conducting.material and may be formed by a hollow tube in the manner illustrated,the bridging member completing the cir cuit between the contacts 1 and 2in the closed circuit-position shown. 3

For the purpose of effecting a blast of on across one of the arcs formedduring opening of the switch to cause interruption of the circuit, theinsulating casing 4 substantially encloses both pairs of contacts sothat the pressure genmechanically strong and, by way of examp1e, may

erated by arcing at one pair is effective to cause a blast of oil acrossthe arc formed at the other pair. Since the insulating casing 4 issubjected to bursting pressures, the structure should be G be alaminated structure impregnated with a phenolic condensation productcured under heat and pressure. In the present construction the casing 4is formed by two sections which are suitably secured and clampedtogether as at 17, the upper section being clamped in position by thestuds 10 and 11 to the lower enlarged ends of the lead-in conductors 8and 9. The lower section of the casing is provided with openings 18 and19 in which the contact portions of the bridging member 3 are guided.

In the operation of circuit breakers of the oilblast type it may beundesirable to subject the entire arcing chamber to high pressures andto move an unnecessarily large amount of oil in creating the circuitinterrupting blast. Excessive pressures within the arcing chamber maycause damage to or destruction of the casing and often oil throw duringcircuit interruption which is very "objectionable. For thepurpose oflocalizing the high pressures within the insulating casing 4, and formoving a minimum amount of oil in creating the oil blast, the arcingchamber comprises a comparatively small .bulbular pressure generatingchamber 20 having a restricted exhaust operiing 21 which is continuouswith a diverging nozzle-like passage 22 near the outer or exhaust end ofwhich the contact 2 and bridging member 3 coact. Accordingly, thepressure generated by arcing in the chamber 20 when the switch is 0opened is effective to cause a high velocity blast of oil through thenozzle-like passage 22 'and the are formed near the exhaust portionthereof and into the main oil body exteriorly ofthe arcing chamber. Inorder completely and effectively to subject'the arc to the action of theoil blast,

.the exhaust opening of the passage 22 is provided with a plurality ofinsulating bafiles or arc splitters 23 which are preferably stream-linedand arranged transversely of the length of the are so that the oil blasttends to divide the are into a plurality of sections. With thisarrangement the sure equalizing apertures 24 communicating with thehollow interior of the bridging member 3 permit a certain relief ofpressure through the opposite end of the bridging member which is open.By arranging the pressure relief apertures 24 along the sides of thebridging member in the chamber 20 there will be no flow of -oil acrossthe pressure generating are into the .bridging member so as to cause anundesirabledecrease in the intensity of the pressure generating arebefore the circuit is finally interrupted.

In case the circuit breaker is used for carrying heavy load currents,the arcing-contact structure above described is generally inadequate andprimary or main current-carrying contacts are also necessary. For thispurpose the actuating rod 16 at its lower end has mounted thereon alaminated bridging member 25 arranged to engage in the closed circuitposition the stationary contacts 26 and 27 which are formed asconducting rings mounted exteriorly of and surrounding'the insulatingcasing 4 and connected to the lead-in conductors as at 28 and 29,respectively. Ac-

cordingly, upon downward or circuit opening movement of the actuatingrod 16, which may be bifurcated as shown to extend on opposite sides ofthe casing 4, the main current-carrying contacts separate prior to thearcing contacts shown by reason of the overtravel of the lattercontacts, continued lowering of the bridging member 3 causing initialseparation of the contacts 1, 3 to form the pressure generating arc andsubsequent separation of the contacts 2, 3 to form the are which isdriven by the oil blast between the arc splitters and extinguished. Theopening stroke may carry the contacts of the bridging member 3 outsideof the arcing chamber in which case the .arc is extinguished prior touncovering of the openings 18 and 19. Immediately after circuitinterruption, the arcing chamber is refilled with oil through thevarious openings and the breaker is in readiness for reclosure and asubsequent opening operation.

In the construction shown in Fig. 2 the insulating casing 4, which issupported as by the bracing members 6' and 'l at the lower ends ofthe'insulating lead-in bushings 6 and 7 is arranged so that the oilblast is directed downwardly into the body of oil and the relativelymovable contacts operate through opposite sides of the casing. Theinsulating casing forming the arcing chamber is in general constructedsimilarly to that described in Fig. 1- with the exception that bothsectionsot the casing are provided with oppositely disposed aperturesfor receiving the contacts 30 and 31 for causing the pressure generatingarc and contacts 32 and 33 arranged adjacent the exhaust of thenozzle-like passage 22 through which the oil blast is directed. In thisarrangement the actuating means for the contacts comprises a pair oflever arms 34 and 35 pivotally connected, as at 36 and 37, with respectto the bushings 6 and 7, so that simultaneous rotation of said arms inopposite directions, as in jawfashion, causes engagement anddisengagement of the aforesaid contacts. ,The upper extremities of thearms 34 and 35 are connected by the insulating links 38 and 39 to thelift rod 40 so that reciprocal vertical movement of said lift rod causesjaw-like operation of the arms 34 and 35. The contact 30 is suitablyinsulated from the conducting arm 34, as at 30', and connected to thelead-in conductor 9 by a flexible insulated 'lead 9', arm 35 is suitablyinsulated at its pivot from conductor 9 and a flexible conductor 34'connects conductor 8 to the arm 34 so that 0on v tacts 30, 31 and 32, 33form two breaks in series.

arcing-contacts being normally biased into engagement as by a spring 41mounted within a recess 42 in the corresponding switch arm in which thearcing contact is guided. It will be apparent, of course, that contacts30 and 32, for example. may be fixed and the arm 35 mounted for pivotalmovement to open and close the contacts.

If desired, the contacts may be formed as hollow tubes, as shown incontacts 32 and 33, for the purpose of relieving excessive'pressures onthe contact mechanism. The degree of pressure relie! is, of course, amatter of design depending upon the interrupting capacity of the switchand other factors.

As in the case ofFig. 1, the opening operation includes separation ofthe primary contacts, if such are used, after which an initial pressuregenerating arc is formed by separation of contacts 30 and 31 in thechamber- 20. The resulting oil blast through the passage 22 drives theare formed between the contacts 32 and 33 between the arc splitters 23,thereby interrupting the circuit. In this design there is no unbalanceof forces and, as in the previous case, the pressure is localized in thechamber 20 and the quantity of oil in the passage 22 is comparativelysmall, so that a high velocity blast is directed through the are formedadjacent the arc splitters 23.

In certain cases it may be desirable to create the oil blast by a springactuated piston or the like, the piston being released in any suitablemanner upon opening of the switch. For the purpose of simplicity theusual accelerating springs for causing high speed opening of the switchhave been omitted.

It should be understood that my invention is not limited to specificdetails or construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the artwithout departing from the spirit of my invention.

' What I claim as new and desire to secure by Letters Patent of theUnited States, is-- 1. An electric circuit interrupter of the oilblasttype comprising relatively movable contacts forming two breaks inseries, an insulating casing having a diverging nozzle-like passagewithin and near the exhaust of which an are at one break is formed uponopening of said contacts, an insulating liquid within said casing, and aplurality of insulating bailles forming are splitters disposed at saidexhaust opening transversely of the length of said arc, the are at theother break causing a blast of insulating liquid through said passageupon separation of said contacts, said are splitters arranged so thatthe arc is driven into the same by said blast and extinguished.

2. An electric circuit interrupter of the oil-blast type comprisingrelatively movable contacts forming two breaks in series, an insulatingcasing immersed in and containing an insulating liquid. said casinghaving a bulbular pressure chamber and a nozzle-like exhaust passage inwhich the arcs at said breaks are formed respectively. and a pluralityof insulating baflles disposed at the exhaust opening of said passage,the pressure generated by arcing within said chamber causing a blast ciinsulating liquid through said passage 3nd driving the other are betweensaid insulating allies.

i 3. An electric circuit interrupter comprising like exhaust passage,the contact ends of said bridging member extending through the walls ofand within said chamber and passage respectively for engaging said fixedcontacts, and a plurality of insulating baflles disposed at the exhaustopening of said casing, the arcingpressure generated in saidchamberduring opening movement of said bridging member causing ablast ofinsulating liquid through said passage for driving the are formed.therein between said insulating baffies. Y

4. An electric circuit interrupter oi the oil-blast type comprisingrelatively movable contacts ineluding a pair of fixed contacts and amovable tubular bridging member for connecting the same, an insulatingcasing forming a pressure generating chamber and a communicating exhaustpassagein each or which a fixed contact is disposed.

the contact ends or said bridging member extending through a wall ofsaid casing to engage said fixed contacts, said member provided withapertures at the opposite ends thereof tending to equalize arcingpressure on said bridging member upon opening of the circuit. I

5. An electric circuit interrupter or the oil-blast type comprising acasing immersed in an insulating liquid forming a pressure generatingchain.-

ber and an exhaust passage, and relatively movable contact structureincluding a pair 0! arms pivoted for jaw-like movement and a pair 0!contacts carried by each arm arranged to extend through apertures insaid casing and cooperate to form, a pressure generating arc in saidchamber and an arc in said exhaust passage, said lastnamed are beingtraversed by a blast of insulating liquid created by-the pressure insaid chamber.

6. An electric circuit interrupter of the oilblast type comprising apair or fixed contacts, a coacting movable bridging member forming withsaid contacts two breaks in series, and a casing containing aninsulating liquid within which said breaks are located, said casingcomprising a substantially nozzle-shaped structure forming a. bulbularpressure generating chamber within which one of said breaks is located,and a diverging exhaust passage in whichthe other break is locatedleading from said chamber.

samurai J. sPURqEoN.

